Transducers generally convert electrical signals to mechanical signals or vibrations, and/or mechanical signals or vibrations to electrical signals. Acoustic transducers, in particular, convert electrical signals to acoustic signals (sound waves) and convert received acoustic waves to electrical signals via inverse and direct piezoelectric effect. Acoustic transducers generally include acoustic resonators, such as surface acoustic wave (SAW) resonators and bulk acoustic wave (BAW) resonators, and may be used in a wide variety of electronic applications, such as cellular telephones, personal digital assistants (PDAs), electronic gaming devices, laptop computers and other portable communications devices. BAW resonators include an acoustic or resonator stack disposed over an acoustic reflector. For example, BAW resonators include thin film bulk acoustic resonators (FBARs), which include resonator stacks formed over a substrate cavity, which functions as the acoustic reflector, and solidly mounted resonators (SMRs), which include resonator stacks formed over alternating stacked layers of low acoustic impedance and high acoustic impedance materials (e.g., an Bragg mirror). The BAW resonators may be used for electrical filters and voltage transformers, for example.
As the need for reductions in the size of components increases, there is a need to reduce the footprint of individual devices, such as FBARs and components (e.g., filters) comprising a plurality of FBARs. Moreover, as power demands increase, there is a need to improve the heat dissipation of individual FBARs, and components comprising a plurality of FBARs.
What is needed, therefore, is a BAW resonator that overcomes at least the shortcomings of known BAW resonators described above.